[unreadable] Small animal imaging has become a powerful tool for drug development and for the understanding of diseases. With animal models widely used in basic and pre-clinical sciences, finding ways to conduct animal experiments more accurately and efficiently is now a key factor in the success and timeliness of research. The recent evolution in molecular biology and genomics has created a large demand for transgenic laboratory animals. In oncology, the use of radiopharmaceuticals for the non-invasive diagnosis of cancer has long been established. And now, small animal PET imaging is being used extensively for tumor targeting by the use of metabolic, transport and receptor-mediated processes to deliver the imaging agent for cancer diagnostic in tumor bearing small animal. The use of high resolution microCT images will augment the performance of functional imaging currently obtained with our microPET by providing accurate identification and localization of normal organ or tumor volume. The combined technologies will allow for the study of disease progression in longitudinal studies and response to therapy over time. Other applications, including pulmonary, cardiology, immunology and orthopedic surgery will all benefit from higher resolution anatomical information. These images will also be used to improve the quality of functional images by providing an accurate attenuation correction. This proposal from Washington University, School of Medicine, is to request funds for the purchase of a 40 micron spatial resolution small animal X-ray CT camera. This instrument will be made available to researchers of many disciplines at Washington University. [unreadable] [unreadable]